The commission may upon complaint of any interested person or upon its own initiative at once and, if it so orders, without answer or other formal pleading by the interested carrier or carriers, but upon reasonable notice, enter upon a hearing concerning the lawfulness of the rate, fare, or charge, or the rule, regulation, or practice, and pending the hearing and the decision thereon the commission, by delivering to the carrier or carriers affected thereby a statement in writing of its reasons therefor, may suspend the operation of the schedule and defer the use of the rate, fare, or charge, or the rule, regulation, or practice. From the date of ordering a hearing to investigate the lawfulness of the rate, fare, or charge, the commission shall have up to six months to complete its investigation. If the commission fails to issue a final order within the six-month period then the changes proposed by the carrier shall go into effect. At any hearing involving a change in a rate, fare, charge, or classification, or in a rule, regulation, or practice, the burden of proof shall be upon the carrier to show that the proposed changed rate, fare, charge, classification, rule, regulation, or practice, is just and reasonable.
HRS § 271G-17